docs: def _is_possible_token(token, token_length=6):
      """Determines if given value is acceptable as a token. Used when validating
      tokens.
  
      Currently allows only numeric tokens no longer than 6 chars.
  
      :param token: token value to be checked
      :type token: int or str
      :param token_length: allowed length of token
      :type token_length: int
      :return: True if can be a candidate for token, False otherwise
      :rtype: bool
  
      >>> _is_possible_token(123456)
      True
      >>> _is_possible_token(b'123456')
      True
      >>> _is_possible_token(b'abcdef')
      False
      >>> _is_possible_token(b'12345678')
      False
      """
      if not isinstance(token, bytes):
          token = six.b(str(token))
      return token.isdigit() and len(token) <= token_length